1. Field of the Invention
The present invention relates to a display device with a touch sensor.
2. Description of the Related Art
A variety of electronic devices provided with display devices, such as a cell phone, a smartphone, a personal computer, a tablet terminal, a portable game machine, and a portable music player, have recently come into widespread use. More intuitively operable electronic devices can be each obtained by providing a touch sensor so as to overlap with a display portion for image display as an interface of such a portable electronic device.
In the display portion, a liquid crystal display device, a display device including an organic electroluminescence (EL) element, an electronic paper performing display by an electrophoretic method, or the like is used.
Typical touch sensors are of resistive type and of capacitive type; besides, a variety of types such as a surface acoustic wave type and an infrared type are known.
As a method for providing a touch sensor so as to overlap with a display portion of a display device, the following method is often employed. A display panel including the display portion for image display and a touch panel including the touch sensor are separately formed and then they are overlapped with each other. In recent years, a reduction in the total weight and a reduction in the manufacturing cost by incorporating a touch panel into a display panel have been considered. For example, Patent Document 1 discloses a structure of a liquid crystal display device in which a touch sensor (referred to as a digitizer sensor board or the like) is provided between a color filter and a substrate over which the color filter is formed.